More advanced scoring scheme
A direction component, realised as a function of the vector dkl
An orientation component, reflecting the difference in reference frames around ak and bl (after superposition)
A sequence component gkl, calculated as an increasing function of |k-i| + |l-j|. This should damp the contribution from near neighbours in the sequence
A spatial component hkl, calculated as a decreasing function of dik + djl, where dik is the distance between ai and ak. This will damp the contribution from large distances in space (want high contribution from pairs near in space and far in sequence)